Hi halfwhitts,
This is not that unusual with manufacturers that have multiple outlets where some of the staff is not as knowledgeable as others. The good news is that there is always access to the information you need … even if one salesperson doesn’t know.
I would compare their quality based on their density just like any polyurethane foam without regard to whether one was “plant based” or not. Higher density foams are more durable. So called “plant based foam” has replaced a small part of one of the two main petrochemicals (the polyol) used to make the foam with an alternative that is chemically derived from plant oils. You can read more about them in post #2 here.
Talatech is a brand name for blended Talalay latex made by Latex International. Talalay latex comes in two versions. One of these is blended (which is a 30% natural and 70% synthetic rubber blend) and the other uses only 100% natural rubber. Because there are also other substances used to make latex foam (soaps, curing agents, fillers, gelling agents, antioxidants, and others) the actual rubber in the 100% natural rubber version would be less than 100% of the entire foam core even though all the rubber itself is 100% natural.
The blended Talatech Talalay is rated with specific ILD’s (see the list here) while the 100% natural comes in softness ratings from N1 to N5 which each represent a range of ILD’s (see here). The blended is a little bit more durable than the 100% natural … particularly in lower ILD’s. If a material has a specific ILD that is one of the ILD’s used for blended Talalay (such as 19 ILD) … then it’s almost certainly the blend … not the 100% natural. You can read more about the difference between the two types of Talalay latex in post #2 here.
Latex itself is a very high quality material but there are several different types. There is also more about the different types of latex in post #6 here.
Phoenix